IV Population Policy In a sense, all the policies of a nation that involve the welfare of the nation's people are population policies, but we are concerned here with policies related to changes in the quantity and quality of the population and its geographical distribution-in the numbers of human beings, their education and skills, and where and how they live relative to the space and resources available to each person. As we have shown, the rate of change of population size, the levels of fertility and mortality, the distribution of people between urban and rural environments, and the rate of change of this distribution significantly interact with the social and economic welfare of people. Two KINDS OF POPULATION-RELATED POLICIES: POPULATION-RESPONSIVE AND POPULATION-INFLUENCING The governments of nearly all countries are committed to improving the welfare of their peoples, and population-related policies are one of the tools available to them for this purpose. Present rates of population growth are so high in most less developed countries that two kinds of policies are called for: population-responsive policies that will ameliorate or overcome the effects of unprecedented increases in population size and density, high birth rates, and high population growth rates; and population-influencing policies that will bring about a reduction in fertility and mortality and in growth rates, or will beneficially influence internal migration. Policies concerning employment, food supply, building of cities and towns, and resource development are in the first category; family planning programs and other policies to reduce fertility, public health and nutrition programs that lower mortality, and transportation and industrial planning to influence internal migration are in the second. In much of the following discussion, we shall concentrate on population-influencing policies aimed at fertility reduction. We recognize that in several developing countries with large land areas, relatively sparse populations, and high fertility rates, government leaders may consider the need for a largeronmental problems of the high income countries, correlated with a high degree of industrialization, mechanized transport, and high fuel use, have not yet appeared in poorer countries and are not likely to show up for some time, given low income levels. Here again, the experience of the richer countries could provide useful indicators of impending trouble.